This invention relates to a furnace that is useful in safely detonating or demilitarizing munitions or explosives, particularly small caliber munitions. The preferred variation of the invention includes a series of chambers having a set of runners or tracks passing amongst the various chambers to allow movement of the munitions from chamber to chamber in trays. The first chamber is heated in such a way so that a tray of munitions placed on the runners in this chamber are baked and detonated. After the detonation is generally complete, the tray containing the then-detonated munition fragments is slid through an opening at the end of that heated detonation chamber into a first cooling chamber. Generally, this movement takes place by addition of another tray containing non-detonated munitions into the first chamber. The furnace may also contain a second cooling chamber to assure both that the subject munitions are detonated and to allow then-safe exiting of the completely detonated munitions from the second cooling chamber onto an external extension of the track. The furnace is configured so that the munitions, whether detonated or not, remain in trays which may be slid through an operating unit without substantial hazard. The invention preferably includes a scrubber for removing noxious or deleterious components of gases produced by the detonation before it is passed into the atmosphere. Finally, the invention includes a method of using a chambered furnace to detonate small arms munitions or other explosives in the manner outlined above.
Sportsmen and the armed services buy and store ammunition prior to its eventual use. However, the shelf life of ammunition is not particularly lengthy. Additionally, if the ammunition if improperly stored, perhaps in the presence of excess or widely varying heat or moisture or pressure, the chemical compounds used in propelling the munition payload may become unstable or inert. After some period of time, the ammunition is simply considered unfit for use. At some military installations, old ammunition was simply buried in a landfill with the understanding that landfills would not be disturbed. However, due to the demilitarization of many military installations and the potential for contamination of ground water, ammunition disposed of in such way has become a liability to be dealt with.
Demilitarization of munitions that have been buried or are simply past useful date by incineration in an open pit was practiced for many years. However, with the imposition of clean air regulations over the past several years, such open air incineration is no longer a viable alternative for disposal of ammunition.
There are a variety of ways to deal with material such as this. Many of the procedures and devices already known are specific in their intent to recycle, e.g., cartridge cases for reloading. One such procedure is shown in U.S. Pat. No. 5,434,336, to Adams, et al. Adams shows a method for stabilizing xe2x80x9cenergetics,xe2x80x9d including explosives, propellance, pyrotechnics, and obsolete munitions via process of reaction or liquid sulfur. The reaction products are suitably non-explosive and safe.
Another process for chemically demilitarizing a small caliber cartridge is with the intent that the cartridge cases be reused, is found in U.S. Pat. No. 5,714,707, to Ruia. The various cases are flushed with a chemical solution such as sulfuric acid to dissolve a bonding material holding the components of the explosive primer mix together. After dissolution of that binder, the primer mix breaks apart and flows into the case. After removal of the explosive primer, the deprimed cases are rinsed and used for reloading or in scrap recovery. The sulfuric acid is said both to desensitize the primer composition without inducing significant stress cracking in the cases.
There are a variety of incinerator-based methods and devices useful in demilitarizing ammunition. These procedures generally are not used with the intent of reusing the cartridges, but instead, produce only reclaimable metals.
U.S. Pat. No. 5,207,176, to Morhard, et al., describes a process for treating such materials using a rotary kiln having a helical flight within. Similarly, U.S. Pat. No. 5,522,326, to Vollhardt, also shows a rotary kiln used variously on ammunition or on material containing chemical warfare agents.
U.S. Pat. No. 5,582,119, to Barkdoll, shows a vessel containing a hot granular bed of material (such as sand) to ignite explosive waste and to dampen any forces generated by the ignition of that waste.
U.S. Pat. No. 5,423,271, to Schulze, shows a process for use of incineration trays for the decomposition of various explosives. The trays are passed through a furnace as a part of a conveyor-like train.
U.S. Pat. Nos. 5,613,453; 5,884,569, and 6,173,662 all to Donovan, show an explosion chamber made up of a double walled, steel structure anchored to a concrete foundation. The explosive chamber has double walled access doors for charging materials to be destroyed. The floor of the chamber is covered with granular shock damping bed such as pea gravel.
U.S. Pat. No. 5,649,324, to Fairweather, et al., discusses a general use of an incineration reactor to deflagrate explosives. xe2x80x9cDeflagrationxe2x80x9d is generally the non-explosive reaction of explosive material. The Fairweather, et al. patent describes methods for recovery of heat and removal of difficult gases from reaction products.
U.S. Pat. No. 5,660,123, to Tadmore, shows a procedure for batchwise destruction of various kinds of explosive materials by adding them to a combustion furnace holding a burning coal bed.
U.S. Pat. No. 5,727,481, to Voorhees, et al., describes a mobile armored incinerator suitable for burning explosive materials. The device has armored walls capable of withstanding internal explosions. It is made up of a variety of sections, a primary chamber for incineration, a secondary combustion chamber to burn exhaust from the primary chamber, and a trailer for providing transportation.
U.S. Pat. No. 5,881,654, to Fleming, et al., shows a device for pyrolizing explosives using a multizoned chamber having a remote combustion zone and an attached device for separating the various products of the combustion.
U.S. Pat. No. 5,907,818, to Hebisch, et al., shows a method of using a rotary cylindrical furnace and separating the resulting reaction products.
None of the devices or procedures shown in any of the documents discussed above are similar to the furnace and procedure for its use shown below.
This invention deals with a furnace for controllably detonating explosive materials, preferably small arms munitions, but also explosives, fireworks, and the like. The furnace itself preferably has several chambers. The first chamber is a heated detonation chamber defined by containment walls. At least a portion of the containment walls are resistant to detonation of the small caliber munitions, e.g., both the flying shrapnel and the percussive forces. The walls internal to the furnace need not be so resistant, but desirably are. The heated detonation chamber preferably has a first opening which is sealable or closable. This opening is for introducing undetonated small caliber munitions to the heated detonation chamber, preferably on a tray. The first or heated detonation chamber has a second opening in a separator wall for removing the detonated munitions from the heated chamber. The second opening preferably is also closable but need not be. The furnace has at least one movable covering for closing the first sealable opening into the heated detonation chamber. The furnace also includes a set of tray runners or tracks that extend generally from the first sealable opening to the second sealable opening and are adapted to slidably support trays containing the detonated or undetonated munitions from the first sealable opening through the second opening. They tray runners or tracks preferably then pass through the optional cooling chambers adjacent the detonation chamber. The furnace is adapted in such a way that introduction of the tray through the first sealable opening into the heated detonation chamber pushes a tray already in the detonation chamber into the first cooling chamber. This action pushes a tray in the first cooling chamber into a second cooling chamber and, in turn, pushes a tray from the second cooling chamber through an exit opening at the exit end of the furnace for access by a furnace operator. The walls of the first and second cooling chambers may be containment walls that are resistant to detonation of the small caliber munitions. The wall between the second cooling chamber and the first cooling chamber may be a partial wall or baffle. Preferably, the heated detonation chamber includes a funneling baffle that extends the length of the chamber and directs detonated munitions fragments flying about within the chamber back to the tray residing on the tray runner or tray track.
The furnace preferably includes a burner situated so that the small arms munitions residing in a tray in the heated detonation chamber are indirectly heated through the tray or are xe2x80x9cbaked.xe2x80x9d The burner preferably is hydrocarbon fired, e.g., by a gas such as methane, propane, or butane. The device may, of course, also use liquid fuels such as kerosene or gasoline.
The inventive furnace preferably includes a scrubber to remove deleterious gases such as sulfur dioxide or trioxide or nitrogen oxides. The scrubber preferably sits adjacent a gas outlet above the heated detonation zone and is protected by an internal baffle.
The invention includes a method of controllably detonating small caliber munitions made up of the steps of: providing a heated detonation chamber having a first opening for introducing undetonated small caliber munitions to the heated detonation chamber and a second opening in a separator wall for removing then-detonated small caliber munitions from the heated detonation chamber. The heated detonation chamber preferably has tray tracks or runners extending between the first sealable opening and the second opening and those tray runners are adapted to slidably support a tray passing through the first sealable opening, through the heated detonation chamber, and through the second opening. The tray tracks or runners are adapted to support the tray during heated detonation of the small caliber munitions. The method further includes the steps of providing some amount of small caliber munitions in a first tray to that heated detonation chamber in a first tray, detonating the small caliber munitions to produce detonated small caliber munitions, and then withdrawing the detonated small caliber munitions and the first tray from the heated detonation chamber. The procedure may include the further steps of introducing a second tray into the heated detonation chamber and pushing the first tray along the tray runners into the first cooling chamber. The process optionally further includes the step of introducing a third tray containing small caliber munitions into the heated detonation chamber and pushing the first tray into a second cooling chamber and pushing the second tray into a first cooling chamber along the tray runners. The process may include another step of introducing a fourth tray into the heated detonation chamber and pushing variously the first tray from an exit in the second cooling chamber, the second tray into the second cooling chamber, and the third tray into the first cooling chamber along the tray tracks. The process generally includes the ancillary steps of moving a covering that is resistant to detonation of the small caliber munitions to close the first sealable opening after introduction of the first tray containing small caliber munitions into the heated detonation chamber. Also included are the steps of detonating the small caliber munitions by heating the heated detonation chamber and scrubbing deleterious gaseous components produced in the detonation step using a scrubber that is in communication with the heated detonation chamber.